A pressure sensor (or transducer) converts a pressure acting thereon to an electrical signal as a function of the pressure imposed. These sensors are generally embodied in pressure sensor packages, and include a pressure-sensing device such as a silicon die. Such devices are typically manufactured using micro-machined or Micro-Electro-Mechanical System (MEMS) based techniques. One common technique for manufacturing a pressure sensor package is to attach a MEMS device onto a substrate, such as a ceramic or printed circuit board (PCB) substrate. Enabling circuit components such as application-specific integrated circuits (ASICs), as well as conductive bonding pads and/or electrical traces, may be mounted to or formed on the substrate for electrically connecting to the MEMS device to perform desired functions (e.g. analog to digital conversion and/or amplification).
Various pressure sensor topologies have been developed for a wide variety of applications. One important field of use includes medical applications for monitoring, for example, the heart rate of a patient. Existing sensors used in this field, including wearable devices, utilize a gel-filled housing for transmitting pressure waves from a sensing end thereof that is arranged in contact with a patient, to a pressure-sensitive die also arranged within the gel-filled housing. In addition to providing a pressure-transmitting medium, the gel acts to protect electronic components of the sensor package from moisture and other detrimental environmental characteristics, for example. These gel-filled sensors, however, suffer several drawbacks. Notably, the gel used in these embodiments is subject to damage if excessive force is applied to exposed surfaces thereof. Likewise, excessive cyclical loads placed on the gel can damage the electrical components of the package, including the bond wires used to establish electrical connections between sensor elements. As the gel has significant mass, these pressure sensors also tend to be sensitive to accelerative forces, which can lead to inaccurate measurements.
Alternative pressure sensor systems and methods are desired.